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RPM surge at startup
Posted: Fri Sep 27, 2002 10:17 am
by amccdadbec
I have a '93 Legacy, 4 cylinder, non-turbo. When I start it in the
morning the RPMs soar to over 2500 then back down to where it almost
stalls. This lasts for about 20 seconds then it runs fine. I've
replaced plugs and PVC. My 92 Legacy starts up and idles just fine.
I'm confused. Please help. Thanks.
Andy
RPM surge at startup
Posted: Tue Oct 01, 2002 2:55 am
by Josh Colombo
What octane gas you running? Have you tried doing any diagnostic stuff?
I've got info on my page
www.surrealmirage.com/subaru
Josh
RPM surge at startup
Posted: Tue Oct 01, 2002 7:32 am
by amccdadbec
I'm running 87 octane. I have a Haynes manual and am going to check
ISC. Thanks for reply.
Andy
RPM surge at startup
Posted: Tue Oct 01, 2002 1:02 pm
by scott b
thats your cold start regulator. i bet it doesnt
happen on warm days or when the engine is warm
RPM surge at startup
Posted: Tue Oct 01, 2002 2:12 pm
by amccdadbec
You're right. It does not happen when the engine is warm. Is this
an electrical part that I can replace? Thanks for info.
Andy
RPM surge at startup
Posted: Tue Oct 01, 2002 2:12 pm
by ciper_
Id guess you just need to clean the IAC. It has a stepper controlled
valve and a temperature spring. The reason it doesn’t happen when its
warm is the the temp spring has now went far to one side, the only
control is by the stepper.
When the stepper gets stuck it pulls hard then pops open. The Ecu senses
the high idle and closes the valve. This repeats.